This invention relates to a fire alarm or similar system, and more particularly to a microprocessor-based system in which serial synchronous power transmission and data communication are provided between a central station or panel and groups of terminal units; such system functioning, by means of independently operable loop controllers, to signal or indicate alarm conditions and the like so that supervisory personnel can be adequately warned of hazardous conditions.
In a fire alarm system of the type just described, groups of terminal units are addressed by a so-called polling routine so that a microprocessor in the respective independent loop controllers can determine the alarm states, if any, of its terminal units on a continuous basis. Thus, each of the many units, for example 100 units on a given loop or line, can be addressed cyclically, e.g., once every several seconds or so. If a given unit during any cycle is determined to be in the alarm state, then that information is communicated to the associated loop controller, and therefrom to a master controller so that a warning to supervisory personnel can be given.
When one or more units are found to be in alarm, the information is displayed on the central panel. Such information is also printed out by a printing device. Meanwhile, information is obtained by the loop controller, for example, as to the type of terminal unit that is in the alarm state, and its location. Moreover, the loop controller, upon receiving notification of an alarm status sends a command to the particular terminal unit in alarm to illuminate its light emitting device so that personnel stationed nearby may precisely locate the outbreak of fire.
A fuller understanding of the operation of such a fire alarm system will be gained as the description of a detailed embodiment of the present invention proceeds. At that time, reference will be made to FIG. 1, in which the context of the invention is depicted, such context being a known fire alarm system of the type just described.
Accordingly, it is a fundamental object of the present invention to provide specialized testing or checking of the loops involved in the described fire detection system or the like, so as to be able to pinpoint the location of discontinuities or breaks in the wiring of such loops.
Another object is to report back to a central controller, as the testing procedure is being carried out, so that an indication can be provided at the central control panel that, in one testing mode, certain ones of the terminal units (detectors) appear to be isolated, i.e., they do not report back when addressed; and, in another testing mode, certain others appear to be isolated.